1. Field of the Invention
The invention concerns a system for hitching a trailer to a motor vehicle, in particular hitching a trailer to a motor tractor, including an imaging sensor, which is located in the area of the hitch.
2. Related Art of the Invention
The hitching of a trailer to a motor vehicle such as a motor tractor is often associated with effort and difficulty and very often requires the cooperation of various persons. Generally the coupling of the trailer to the motor tractor occurs in that the motor tractor moves backwards towards the trailer until the coupling device located on the trailer has approached the coupler or hitch located on the motor tractor to the extent that both can be connected to each other. The driver of the motor tractor has, however, while driving backwards, no view of the field of action, and attempts, blindly, to superimpose the coupling parts of the trailer and the motor tractor. Therein it frequently occurs that the operator drives too close to the trailer so that the tow bar damages the back end of his motor tractor. In this manner damage frequently occurs when the coupler of the motor vehicle is not precisely aligned with the ball-shaped head of the trailer tow bar, or the backing up ceases prior to the coupling process so that an offset remains in the longitudinal and/or transverse direction. In each case the driver must exit the vehicle and investigate the position of the coupler with respect to the trailer tow bar, in order then to try again, since the manual movement of the tow bar in the case of heavy trailers is, as a rule, impossible.
Further, it is known to employ motor vehicles with collision warning devices, wherein the collision warning device includes for example ultrasound sensors, which can determine the distance to other objects in close proximity to the vehicle. Herein the collision avoidance devices are so designed, that a warning signal is emitted upon exceeding a predetermined minimum separation. The collision avoidance devices known until now, which operate on the echo principle, are preferably installed in the cabin area and emit into the area behind the motor vehicle which is not observable by the driver. From this, however, only the type of information can be obtained, which only very generally informs the driver whether an object is located in the rear area of the motor vehicle and what distance this object has from the motor vehicle and when the brakes must be activated. It is herein however a disadvantage that, in many cases, in particular during coupling of the motor vehicle to a trailer, the mere information that an object is present is not sufficient, but rather information is desired regarding the precise location or, as the case may be, position of the object.
From DE 102 37 615 C1 a process and device are known for positioning the coupling device or hitch of the trailer relative to a coupler of a motor tractor. The two couplings have longitudinal axis, which are oriented essentially parallel to each other in that the trailer side coupling device and the motor tractor coupler are moved relative to each other in such a manner, that the same number of receivers on both sides of a central point of the receiver device receive signal emissions from the trailer with the same intensity. Then the two couplings can be moved towards each other using distance measurement by means of a transmitter and a receiver unit. For the positioning of the two coupling elements to each other, not only the distance but also the orientation of their longitudinal axis is determined. In this manner it becomes possible to so direct the motor tractor towards the trailer that the trailer coupling device and the motor tractor coupler are so close to each other that they can be connected to each other and simultaneously the longitudinal axis of the motor tractor aligns with that of the trailer. Therein the transmitter is associated with the longitudinal axis of the motor tractor, while the receiver unit is associated with the longitudinal axis of the trailer. The signal emissions received by the receiver unit are processed via a micro-computer into data to produce spoken or visual displays by means of a computer. In this manner the driver of the motor tractor obtains the information regarding the orientation of the motor tractor coupler relative to the trailer coupling device.